The present invention relates to cargo carrying pallets, both platform and container types, normally used in military aircraft cargo-handling and tiedown systems, and more particularly to an adaptor assembly for converting such military pallets for use with commercial, cargo-handling and tiedown systems.
Pallets are normally used for handling cargo onto and off of cargo carrying vehicles such as cargo airplanes. When the term "pallet" is used herein, it includes a basic platform on which cargo is loaded and then tied to the platform as well as enclosed containers into which cargo is loaded. The construction specifications for pallets used in military cargo-handling systems call for base or bottom dimensions of the pallet to be 88 inches in width and 108 inches in length. The specifications also require the military cargo pallets to be fitted with a plurality of lateral projections that extend outwardly from the sides of the pallet adjacent the bottom. These projections are of equal length and are spaced equidistantly along the entire length of the pallet. Similar longitudinal projections are also required on the two ends of the pallet adjacent its bottom. These projections are designed to function with the military tiedown systems used in military cargo aircraft. Such military tiedown systems employ movable retraining members that are locked over and in-between the lateral projections on the sides of the pallets to restrain both longitudinal and vertical movement of the pallets.
On the other hand, commercial pallets are normally 88 inches in width and 125 inches in length. The commercial pallets are provided with a plurality of inwardly extending pockets or recesses, normally having a rectangular cross-section, located adjacent the bottom of the pallet and spaced along the longitudinal sides of the pallet. Similar recesses are also provided along the two ends of the pallet adjacent its bottom. In a commercial cargo-handling system, movable restraining members, in the form of a bar or other movable members that can be slidably inserted into the recesses, are employed to longitudinally and vertically restrain the pallet once it is in place in the aircraft. Normally, end restraining members in commercial cargo-handling systems are fixed at locations along the cargo bed corresponding to the 125 inch length of the commercial pallets. Side restraining members are also positioned on the cargo bed adjacent the sides of the pallet at locations corresponding to one or more of the side recesses in the commercial pallet.
These commercial restraining members are to some extent effective to tie down a military pallet in the commercial cargo-handling system. However, when military pallets are inserted into a commercial cargo-handling and tiedown system, all or a portion of the commercial end restraining members must be repositioned to accommodate and tie down the military pallets. Since repositioning the end restraining members is a time consuming task, only one tiedown member is repositioned for each military pallet, leaving a relatively large space, for example the difference in length between the military pallet and the commercial pallet, between each successive pallet loaded onto the airplane. When the military pallets are inserted in the commercial aircraft tiedown system in this manner, a substantial amount of space is wasted when 15 or so pallets are longitudinally aligned on the aircraft cargo bed. Moreover, if the military pallets are abutted against each other, the commercial side restraining mechanisms will not properly cooperate with the military pallets to individually restrain the military pallets in both the longitudinal and vertical directions.
Another problem with using military pallets in a commercial cargo tiedown system arises when the military pallets are moved into and out of the aircraft cargo bed. Normally, commercial cargo-handling systems employ a plurality of vertically oriented guide rollers that are spaced along the longitudinal dimension of the aircraft. The rollers form side restraining tracks to prevent excessive lateral movement of the pallet as it is being postioned on the cargo bed and moved from the cargo access opening toward the opposite end of the aircraft. The lateral projections on the military pallets tend to catch on the vertical rollers, as they are spaced at distances greater than the spacing of the projections, thus causing the military pallet to sometimes be checked in its movement to or from the access door on the aircraft. This problem could be resolved by adding additional rollers to the lateral restraining tracks in the cargo-handling system, however this solution involves a substantial amount of labor and a relatively high cost, not justified when the cargo-handling system is normally utilized with smooth-sided commercial pallets.
To resolve the foregoing problems, a broad object of the present invention is to provide an apparatus for adapting a military pallet for use in commercial cargo-handling and tiedown systems. Additional objects of the present invention are: to provide an adaptor that is easy to manufacture from metals such as aluminum; to provide an adaptor that is lightweight so that it can be carried on the airplane when not in use; to provide an adaptor that is easily fitted onto a military pallet with only a very small amount of labor; to provide an adaptor that can accommodate both the side and end restraining members normally used in commercial cargo-handling and tiedown systems; to provide an adaptor that has sufficient versatility and adaptability so that military cargo pallets can be placed on a commercial tiedown system with a minimum of lost space between the pallets; and, to provide an adapter that permits military pallets to be placed in a variety of positions in a commercial tiedown system without disturbing the standard commercial positioning and spacing of the commercial side and end restraining members.